Imaging optical system, projection-type display apparatus, and imaging apparatus

ABSTRACT

The imaging optical system consists of a first optical system and a second optical system in order from a magnified side. The second optical system forms an image on an image display surface as an intermediate image, and the first optical system forms the intermediate image on a magnified-side conjugate plane. A height of a principal ray of light having a maximum angle of view becomes maximum on a lens surface of the whole system on the most magnified side, among heights of principal rays of light having a maximum angle of view on respective lens surfaces. The imaging optical system satisfies predetermined conditional expressions.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. application Ser. No.17/395,115 filed on Aug. 5, 2021, which is a Divisional of U.S.application Ser. No. 16/555,109 filed on Aug. 29, 2019, now U.S. Pat.No. 11,112,587, which is a Divisional of U.S. application Ser. No.15/602,527 filed on May 23, 2017, now U.S. Pat. No. 10,437,027, andclaims priority under 35 U.S.C. § 119 to Japanese Patent Application No.2016-104120 filed on May 25, 2016. The above application is herebyexpressly incorporated by reference, in its entirety, into the presentapplication.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an imaging optical system suitable forbeing used in a projection-type display apparatus having a light valvesuch as, particularly, a liquid crystal display device or a DigitalMicromirror Device (DMD: Registered Trademark) mounted therein, aprojection-type display apparatus including this imaging optical system,and an imaging apparatus including this imaging optical system.

2. Description of the Related Art

In recent years, projection-type display apparatuses (also calledprojectors), such as a liquid crystal display device or a DMD, having alight valve mounted therein have been in widespread use and haveincreased in performance.

In addition, with the recent improvement in the performance of a lightvalve, an imaging optical system which is combined with the light valvehas required satisfactory aberration correction appropriate for theresolution of the light valve. Further, in consideration of use in arelatively narrow indoor space for the purpose of presentation or thelike, an imaging optical system having a wider angle is stronglydemanded.

In order to respond to such a demand, an imaging optical system isproposed in which an intermediate image is formed in a reduced-sideoptical system consisting of a plurality of lenses, and the image isre-formed likewise in a magnified-side optical system consisting of aplurality of lenses (see JP2014-029392A, JP2015-060062A, andJP2005-128286A).

In an imaging optical system constituted by only an optical systemhaving no normal intermediate image formed thereon, in a case where anattempt is made to widen an angle by reducing a focal length, lenses onthe magnified side become excessively large in any way. However, in theimaging optical system of an intermediate imaging type as describedabove, it is possible to shorten the back focus of the magnified-sideoptical system, and to reduce the magnified-side lens diameters of themagnified-side optical system. Therefore, the system is also suitablefor widening an angle by reducing a focal length.

However, there are problems in that imaging optical systems of Examples3 and 5 disclosed in JP2014-029392A are narrow in the angle of view, andthat imaging optical systems of the other examples are wide in the angleof view but are large in lens diameter. In addition, there is a problemin that an imaging optical system disclosed in JP2015-060062A is largein lens diameter. In addition, there is a problem in that an imagingoptical system disclosed in JP2005-128286A is large in distortion and isnot sufficient in imaging performance.

SUMMARY OF THE INVENTION

The present invention is contrived in view of such circumstances, and anobject thereof is to provide an imaging optical system having a wideangle of view in which various aberrations are appropriately correctedand a lens diameter is kept small, a projection-type display apparatusincluding this imaging optical system, and an imaging apparatusincluding this imaging optical system.

According to the present invention, there is provided an imaging opticalsystem capable of projecting an image, displayed on an image displaydevice disposed on a reduced-side conjugate plane, as a magnified imageon a magnified-side conjugate plane, the system comprising, in orderfrom a magnified side: a first optical system which is constituted by aplurality of lenses; and a second optical system which is constituted bya plurality of lenses, wherein the second optical system forms the imageon the image display device as an intermediate image, the first opticalsystem forms the intermediate image on the magnified-side conjugateplane, a height of a principal ray of light having a maximum angle ofview becomes maximum on a lens surface of the whole system on the mostmagnified side, among heights of principal rays of light having amaximum angle of view on respective lens surfaces, and the followingConditional Expressions (1) and (2) are satisfied,

0.03<H×|f|/(L×I)<0.09  (1)

0.35<I|dl  (2)

where H is a height of the principal ray of light having a maximum angleof view on a plane orthogonal to an optical axis through a point ofintersection between the lens surface on the most magnified side and theoptical axis, f is a focal length of the whole system, L is a distanceon the optical axis between the lens surface on the most magnified sideand a lens surface on a most reduced side,

I is a maximum image height on the reduced side, and

dl is a maximum air spacing on the optical axis within the system.

In the imaging optical system of the present invention, it is preferableto satisfy the following Conditional Expression (1-1) and/or (2-1).

0.04<H×|f|/(L×I)<0.08  (1-1)

0.38<I|dl<0.55  (2-1)

In addition, it is preferable to satisfy the following ConditionalExpression (3), and more preferable to satisfy the following ConditionalExpression (3-1),

4<b/a<10  (3)

5<b/a<8  (3-1)

where b is a light flux diameter of a maximum image height in a meridiandirection at an F-Number five times a design F-Number, and

a is an on-axis light flux diameter at an F-Number five times the designF-Number. Meanwhile, the light flux diameters of a and b are set tolight flux diameters on the magnified side rather than the lens surfaceon the most magnified side when a projection distance is set to beinfinite. In addition, the position of a diaphragm for determining theF-Number when a and b are calculated is set to a position at which aprincipal ray of light and an optical axis intersect each other withinthe second optical system. In addition, the light flux diameter of b isset to a light flux diameter in a direction perpendicular to theprincipal ray of light.

In addition, it is preferable to satisfy the following ConditionalExpression (4), and more preferable to satisfy the following ConditionalExpression (4-1),

0.8<H×f ²/(fo×I ²)<1.3  (4)

0.84<H×f ²/(fo×I ²)<1.2  (4-1)

where H is a height of the principal ray of light having a maximum angleof view on a plane orthogonal to an optical axis through a point ofintersection between the lens surface on the most magnified side and theoptical axis,

f is a focal length of the whole system,

fo is a focal length of the first optical system, and

I is a maximum image height on the reduced side.

In addition, it is preferable to satisfy the following ConditionalExpression (5),

1<fo/|f|<1.8  (5)

where fo is a focal length of the first optical system, and

f is a focal length of the whole system.

In addition, it is preferable to satisfy the following ConditionalExpression (6),

1<enp/I<2  (6)

where enp is a distance on the optical axis from the lens surface on themost magnified side to a pupil position on the magnified side, and

I is a maximum image height on the reduced side.

Meanwhile, the pupil position is assumed to be determined by theprincipal ray of light having a maximum angle of view.

In addition, the imaging optical system further comprises: a positivemeniscus lens, located adjacent to a magnified side or a reduced side ofa position at which the intermediate image is formed, in which a concavesurface is directed toward the reduced side; and a negative lens,located adjacent to the reduced side of the positive meniscus lens, inwhich the concave surface is directed toward the magnified side, and itis preferable to satisfy the following Conditional Expression (7), andmore preferable to satisfy the following Conditional Expression (7-1),

0<(Rpr+Rmf)/(Rpr−Rmf)<0.8  (7)

0.2<(Rpr+Rmf)/(Rpr−Rmf)<0.6  (7-1)

where Rpr is a radius of curvature of a surface of the positive meniscuslens on the reduced side, and

Rmf is a radius of curvature of a surface of the negative lens on themagnified side.

According to the present invention, there is provided a projection-typedisplay apparatus comprising: a light source; a light valve on whichlight from the light source is incident; and the imaging optical systemof the present invention as an imaging optical system that projects anoptical image of light optically modulated by the light valve onto ascreen.

According to the present invention, there is provided an imagingapparatus comprising the imaging optical system of the presentinvention.

Meanwhile, the term “magnified side” means a projected side (screenside), and the screen side is assumed to be referred to as the magnifiedside, for the sake of convenience, even in a case of reductionprojection. On the other hand, the term “reduced side” means an imagedisplay device side (light valve side), and the light valve side isassumed to be referred to as the reduced side, for the sake ofconvenience, even in a case of reduction projection.

In addition, the term “consist of” is intended to be allowed to includelenses having substantially no power, optical elements, such as amirror, a diaphragm, a mask, cover glass, or a filter having no power,other than a lens, and the like, in addition to the things enumerated ascomponents.

In addition, the term “lens group” is not necessarily constituted by aplurality of lenses, but may be constituted by only one lens.

In addition, the surface shape of the lens and the sign of therefractive power thereof are assumed to be those in a paraxial region ina case where an aspherical surface is included.

According to the present invention, there is provided an imaging opticalsystem capable of projecting an image, displayed on an image displaydevice disposed on a reduced-side conjugate plane, as a magnified imageon a magnified-side conjugate plane, the system comprising, in orderfrom a magnified side: a first optical system which is constituted by aplurality of lenses; and a second optical system which is constituted bya plurality of lenses, wherein the second optical system forms the imageon the image display device as an intermediate image, the first opticalsystem forms the intermediate image on the magnified-side conjugateplane, a height of a principal ray of light having a maximum angle ofview becomes maximum on a lens surface of the whole system on a mostmagnified side, among heights of principal rays of light having amaximum angle of view on respective lens surfaces, and the followingConditional Expressions (1) and (2) are satisfied. Therefore, it ispossible to form an imaging optical system having a wide angle of viewin which various aberrations are appropriately corrected and a lensdiameter is kept small.

0.03<H×|f|/(L×I)<0.09  (1)

0.35<I|dl  (2)

Since the projection-type display apparatus of the present inventionincludes the imaging optical system of the present invention, it ispossible to project a high-quality image with a wide angle of view, andto reduce the size of the apparatus.

Since the imaging apparatus of the present invention includes theimaging optical system of the present invention, it is possible toacquire a high-quality image with a wide angle of view, and to reducethe size of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a configuration (in commonwith that of Example 1) of an imaging optical system according to anembodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of animaging optical system of Example 2 of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of animaging optical system of Example 3 of the present invention.

FIG. 4 is a cross-sectional view illustrating a configuration of animaging optical system of Example 4 of the present invention.

FIG. 5 is a diagram of aberrations of an imaging optical system ofExample 1 of the present invention.

FIG. 6 is a diagram of aberrations of an imaging optical system ofExample 2 of the present invention.

FIG. 7 is a diagram of aberrations of an imaging optical system ofExample 3 of the present invention.

FIG. 8 is a diagram of aberrations of an imaging optical system ofExample 4 of the present invention.

FIG. 9 is a schematic configuration diagram of a projection-type displayapparatus according to an embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a projection-typedisplay apparatus according to another embodiment of the presentinvention.

FIG. 11 is a schematic configuration diagram of a projection-typedisplay apparatus according to still another embodiment of the presentinvention.

FIG. 12 is a perspective view of a front side of an imaging apparatusaccording to an embodiment of the present invention.

FIG. 13 is a perspective view of a rear surface side of the imagingapparatus shown in FIG. 12 .

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the accompanying drawings. FIG. 1 is across-sectional view illustrating a configuration of an imaging opticalsystem according to an embodiment of the present invention. Theconfiguration example shown in FIG. 1 is in common with a configurationof an imaging optical system of Example 1 described later. In FIG. 1 ,an image display surface Sim side is a reduced side, a lens L1 a side ofa first optical system G1 is a magnified side, and a shown aperturediaphragm St does not necessarily indicates a size or a shape, butindicates a position on an optical axis Z. In addition, in FIG. 1 , anon-axis light flux wa and a light flux wb of the maximum angle of vieware also shown together.

This imaging optical system is mounted on, for example, aprojection-type display apparatus, and can be used in projecting imageinformation displayed on a light valve onto a screen. In FIG. 1 , on theassumption of a case of being mounted on the projection-type displayapparatus, an optical member PP assumed to be a filter, a prism and thelike which are used in a color synthesis portion or an illuminationlight separation portion, and the image display surface Sim of the lightvalve located on the surface of the optical member PP on the reducedside are also shown together. In the projection-type display apparatus,a light flux to which image information is given on the image displaysurface Sim on an image display device is incident on this imagingoptical system through the optical member PP, and is projected onto ascreen, not shown, by this imaging optical system.

As shown in FIG. 1 , the imaging optical system of the presentembodiment consists of the first optical system G1 constituted by aplurality of lenses and a second optical system G2 constituted by aplurality of lenses, in order from the magnified side. The secondoptical system G2 is configured to form an image on the image displaysurface Sim as an intermediate image MI, and the first optical system G1is configured to form the intermediate image on a magnified-sideconjugate plane.

In an optical system for projection constituted by only an opticalsystem having no normal intermediate image formed thereon, in a casewhere an attempt is made to widen an angle by reducing a focal length, alens on the magnified side becomes excessively large in any way.However, in an optical system for projection of a type in whichintermediate imaging is performed as in the present embodiment, it ispossible to shorten a back focus of the first optical system G1, and toreduce lens diameters of the first optical system G1 on the magnifiedside. Therefore, the system is suitable for widening an angle byreducing a focal length.

In addition, the optical system is configured such that the height of aprincipal ray of light having a maximum angle of view becomes maximum onthe lens surface of the whole system on the most magnified side, amongthe heights of the principal rays of light having a maximum angle ofview on respective lens surfaces. Thereby, it is possible to reduce alens outside diameter while maintaining a wide angle of view.

In addition, it is configured to satisfy the following ConditionalExpressions (1) and (2). The ratio value is not set to be equal to orless than the lower limit of Conditional Expression (1), and thus it ispossible to appropriately correct, particularly, distortion andastigmatism, and to make both optical performance and a wide angle ofview easy. The ratio value is not set to be equal to or greater than theupper limit of Conditional Expression (1), and thus it is possible toprevent lens diameters on the magnified side from increasing. The ratiovalue is not set to be equal to or less than the lower limit ofConditional Expression (2), and thus it is possible to prevent theentire length from increasing. Meanwhile, in a case where the followingConditional Expression (1-1) and/or (2-1) is satisfied, it is possibleto make characteristics more satisfactory. The ratio value is not set tobe equal to or greater than the upper limit of Conditional Expression(2-1), and thus it is possible to secure an appropriate lens distance,and to make it easy to correct lateral chromatic aberration and imageplane curvature.

0.03<H×|f|/(L×I)<0.09  (1)

0.04<H×|f|/(L×I)<0.08  (1-1)

0.35<I|dl  (2)

0.38<I|dl<0.55  (2-1)

Here, H is a height of the principal ray of light having a maximum angleof view on a plane orthogonal to an optical axis through a point ofintersection between the lens surface on the most magnified side and theoptical axis,

f is a focal length of the whole system,

L is a distance on the optical axis between the lens surface on the mostmagnified side and a lens surface on a most reduced side,

I is a maximum image height on the reduced side, and

dl is a maximum air spacing on the optical axis within the system.

In the imaging optical system of the present embodiment, it ispreferable to satisfy the following Conditional Expression (3). Theratio value is not set to be equal to or less than the lower limit ofConditional Expression (3), and thus it is possible to secure aperipheral light amount ratio even in a case where a lens is used whichhas a wide angle of view and in which various aberrations aresatisfactorily corrected. The ratio value is not set to be equal to orgreater than the upper limit of Conditional Expression (3), and thus itis possible to prevent a lens diameter from increasing. Meanwhile, in acase where the following Conditional Expression (3-1) is satisfied, itis possible to make characteristics more satisfactory.

4<b/a<10  (3)

5<b/a<8  (3-1)

Here, b is a light flux diameter of a maximum image height in a meridiandirection at an F-Number five times a design F-Number, and a is anon-axis light flux diameter at an F-Number five times the designF-Number.

In addition, it is preferable to satisfy the following ConditionalExpression (4). The ratio value is not set to be equal to or less thanthe lower limit of Conditional Expression (4), and thus it is possibleto appropriately correct, particularly, distortion and astigmatism, andto make both optical performance and a wide angle of view easy. Theratio value is not set to be equal to or greater than the upper limit ofConditional Expression (4), and thus it is possible to prevent lensdiameters on the magnified side from increasing. Meanwhile, in a casewhere the following Conditional Expression (4-1) is satisfied, it ispossible to make characteristics more satisfactory.

0.8<H×f ²/(fo×I ²)<1.3  (4)

0.84<H×f ²/(fo×I ²)<1.2  (4-1)

Here, H is a height of the principal ray of light having a maximum angleof view on a plane orthogonal to an optical axis through a point ofintersection between the lens surface on the most magnified side and theoptical axis,

f is a focal length of the whole system,

fo is a focal length of the first optical system, and

I is a maximum image height on the reduced side.

In addition, it is preferable to satisfy the following ConditionalExpression (5). The ratio value is not set to be equal to or less thanthe lower limit of Conditional Expression (5), and thus it is possibleto make it easy to correct spherical aberration, image plane curvature,and astigmatism. The ratio value is not set to be equal to or greaterthan the upper limit of Conditional Expression (5), and thus it ispossible to prevent a lens diameter in the vicinity of an intermediateimage formation position from increasing.

1<fo/|f|<1.8  (5)

Here, fo is a focal length of the first optical system, and

f is a focal length of the whole system.

In addition, it is preferable to satisfy the following ConditionalExpression (6). The ratio value is not set to be equal to or less thanthe lower limit of Conditional Expression (6), and thus it is possibleto make it easy to correct distortion and astigmatism. The ratio valueis not set to be equal to or greater than the upper limit of ConditionalExpression (6), and thus it is possible to prevent lens diameters on themagnified side from increasing.

1<enp/I<2  (6)

Here, enp is a distance on the optical axis from the lens surface on themost magnified side to a pupil position E, shown in, for example, FIGS.1-4 , on the magnified side, and

I is a maximum image height on the reduced side.

In addition, the imaging optical system includes a positive meniscuslens, located adjacent to a magnified side or a reduced side of aposition at which the intermediate image is formed, in which a concavesurface is directed toward the reduced side, and a negative lens,located adjacent to the reduced side of this positive meniscus lens, inwhich the concave surface is directed toward the magnified side, and itis preferable to satisfy the following Conditional Expression (7). Theratio value is not set to be equal to or less than the lower limit ofConditional Expression (7), and thus it is possible to prevent a lensoutside diameter in the middle of the second optical system G2 fromincreasing. The ratio value is not set to be equal to or greater thanthe upper limit of Conditional Expression (7), and thus it is possibleto prevent a lens outside diameter in the vicinity of the intermediateimage formation position from increasing. Meanwhile, in a case where thefollowing Conditional Expression (7-1) is satisfied, it is possible tomake characteristics more satisfactory.

0<(Rpr+Rmf)/(Rpr−Rmf)<0.8  (7)

0.2<(Rpr+Rmf)/(Rpr−Rmf)<0.6  (7-1)

Here, Rpr is a radius of curvature of a surface of the positive meniscuslens on the reduced side, and

Rmf is a radius of curvature of a surface of the negative lens on themagnified side.

Next, numerical value examples of the imaging optical system of thepresent invention will be described.

First, an imaging optical system of Example 1 will be described. FIG. 1shows a cross-sectional view illustrating a configuration of the imagingoptical system of Example 1. Meanwhile, in FIG. 1 and FIGS. 2 to 4corresponding to Examples 2 to 4 described later, an image displaysurface Sim side is a reduced side, a lens L1 a side of a first opticalsystem G1 is a magnified side, and a shown aperture diaphragm St doesnot necessarily indicates a size or a shape, but indicates a position onthe optical axis Z. In addition, in FIGS. 1 to 4 , an on-axis light fluxwa and a light flux wb of the maximum angle of view are also showntogether.

The imaging optical system of Example 1 is constituted by the firstoptical system G1 and the second optical system G2 in order from themagnified side. The first optical system G1 is constituted by elevenlenses of lenses L1 a to L1 k. The second optical system G2 isconstituted by eight lenses of lenses L2 a to L2 h.

Table 1 shows lens data of the imaging optical system of Example 1,Table 2 shows data relating to specifications, and Table 3 shows datarelating to aspherical coefficients. In the following, the meanings ofsymbols in the tables will be described by taking an example of those inExample 1, but the same is basically true of Examples 2 to 4.

In the lens data of Table 1, the column of a surface number indicatessurface numbers sequentially increasing toward the reduced side with thesurface of a component on the most magnified side set to a firstsurface, the column of a radius of curvature indicates radii ofcurvature of respective surfaces, and the column of a surface spacingindicates distances on the optical axis Z between the respectivesurfaces and the next surfaces. In addition, the column of n indicatesrefractive indexes of respective optical elements with respect to a dline (wavelength of 587.6 nm), and the column of v indicates Abbenumbers of the respective optical elements with respect to the d line(wavelength of 587.6 nm). Here, the sign of the radius of curvature isset to be positive in a case where a surface shape is convex on themagnified side, and is set to be negative in a case where a surfaceshape is convex on the reduced side. The lens data also indicates theaperture diaphragm St and the optical member PP together. In the placeof a surface number of a surface equivalent to the aperture diaphragmSt, a term of (diaphragm) is written together with the surface number.

The data relating to specifications of Table 2 indicates values of afocal length f, a back focus Bf, an F-Number FNo, and the total angle ofview 2ω.

Meanwhile, numerical values shown in data relating to basic lens dataand specifications are standardized so that the focal length of thewhole system is set to −1. In addition, the numerical values of eachtable are rounded off to predetermined decimal places.

In the lens data of Table 1, mark * is attached to the surface number ofan aspherical surface, and the numerical values of a paraxial radius ofcurvature are indicated as the radius of curvature of the asphericalsurface. The data relating to the aspherical coefficients of Table 3indicates surface numbers of the aspherical surfaces and asphericalcoefficients relating to these aspherical surfaces. “E-n” (n is aninteger) in the numerical values of the aspherical coefficients of Table3 means “×10^(n)”. The aspherical coefficients are values of respectivecoefficients KA and Am (m=3 to up to 18) in an aspherical expressionrepresented by the following expression.

Zd=C·h ²/{1+(1−KA·C ² ·h ²)^(1/2) }+ΣAm·h ^(m)

Here, Zd is an aspherical depth (length of a vertical line drawn from apoint on an aspherical surface having a height h down to a planeperpendicular to the optical axis with which the vertex of theaspherical surface is in contact),

h is a height (distance from the optical axis),

C is a reciprocal of the paraxial radius of curvature, and

KA and Am are aspherical coefficients (m=3 to up to 18).

TABLE 1 Example 1: Lens data (n and ν are based on the d line) SURFACERADIUS OF SURFACE NUMBER CURVATURE SPACING n ν *1 −11.9824 0.59121.58313 59 46 *2 4.2802 2.0112  3 11.3341 0.4223 1.83481 42.72  4 2.06371.8461  5 −2.3698 1.6063 1.83481 42.72  6 −3.4655 0.0050  7 4.67000.8559 1.77250 49.60  8 −25.2694 0.7514  9 −3.7273 1.2782 1.80610 33.2710 −4.1602 1.3117 1.59282 68.62 11 7.5741 1.4296 12 −2.7352 0.18281.71736 29.52 13 −73.2107 1.3385 14 7.8650 1.6911 1.49700 81.61 15−2.8675 0.2051 1.80518 25.46 16 −42.3621 1.8543 *17  6.4852 1.31011.58313 59.46 *18  −4.8774 1.0238 19 3.9852 0.7768 1.84666 23.78 206.2029 3.2834 21 −3.0932 1.0135 1.51742 52.43 22 12.9587 0.3367 23−346.6075 1.3162 1.80000 29.84 24 −4.7977 4.2562 25 7.7867 1.04021.59282 68.62 26 −11.6091 3.8300 27 ∞ 0.4856 (DIAPHRAGM) 28 2.65310.1534 1.51742 52 43 29 2.2689 1.0210 30 −2.2729 0.1454 1.84666 23.78 3110.1197 0.7284 1.59282 68.62 32 −3.8164 0.0051 33 45.4997 0.8863 1.5928268.62 34 −3.6908 2.3577 35 12.0795 0.8812 1.89286 20.36 36 −15.00173.0406 1.51633 64.14 37 ∞ 4.2230 38 ∞ 0.0030

TABLE 2 Example 1: Specifications f′ −1.00 Bf′ 5.82 FNo. 2.05 2ω[°]126.6

TABLE 3 Example 1: Aspherical coefficients SURFACE NUMBER 1 2 KA−3.22710352E−01  −5.12420208E+00  A3 2.77841807E−02 4.78947876E−02 A42.85276272E−04 −2.60866800E−02  A5 −1.03627997E−03  3.33058901E−02 A61.08380363E−04 −2.57078731E−02  A7 1.62391178E−05 1.42004634E−02 A8−3.01306781E−06  −5.56679848E−03  A9 1.84123627E−08 1.57318981E−03 A103.91729924E−08 −3.26527884E−04  A11 −3.75509981E−09  4.96148861E−05 A12−1.82713607E−10  −5.48184635E−06  A13 3.00357220E−11 4.27780457E−07 A14−2.54501112E−12  −2.38316223E−08  A15 1.10646340E−12 2.96299823E−10 A161.15328327E−13 −2.06984108E−10  A17 0.00000000E+00 0.00000000E+00 A180.00000000E+00 0.00000000E−00 SURFACE NUMBER 17 18 KA 1.45666692E−01−1.49999945E+01 A3 −4.10191592E−03  −1.22975751E−02 A4 8.80229915E−03 1.47531149E−02 A5 −6.87678586E−03  −3.26414061E−03 A6 3.65219363E−03−2.33907692E−03 A7 −4.01407946E−03   1.26837185E−03 A8 2.63264761E−03−3.92634934E−04 A9 −8.32233769E−04   1.25241685E−04 A10 6.89229504E−05−2.49278838E−05 A11 1.78029344E−05  4.39416157E−07 A12 5.19477138E−06 5.36948473E−08 A13 −5.40371430E−06   2.52132806E−07 A14 1.25757478E−06−7.98650726E−08 A15 −1.11289734E−07   8.69366896E−09 A16 2.06167105E−09−5.41667909E−10

FIG. 5 shows a diagram of aberrations of the imaging optical system ofExample 1. Meanwhile, FIG. 5 shows an aberration diagram at apredetermined projection distance (indicated in the drawing), and showsspherical aberration, astigmatism, distortion, and lateral chromaticaberration, in order from the left side. The diagram of aberrationsindicating spherical aberration, astigmatism, and distortion indicatesaberrations in which the d line (wavelength of 587.6 nm) is used as areference wavelength. In the spherical aberration diagram, aberrationsrelating to the d line (wavelength of 587.6 nm), a C line (wavelength of656.3 nm), and an F line (wavelength of 486.1 nm) are indicated by asolid line, a long dashed line, and a short dashed line, respectively.In the astigmatism diagram, aberrations in a sagittal direction and atangential direction are indicated by a solid line and a short dashedline, respectively. In the lateral chromatic aberration diagram,aberrations relating to the C line (wavelength of 656.3 nm) and the Fline (wavelength of 486.1 nm) are indicated by a long dashed line and ashort dashed line, respectively. FNo. in the spherical aberrationdiagram means an F-Number, and ω in the other aberration diagrams meansa half angle of view.

In the description of Example 1, symbols, meanings, and descriptionmethods of the respective pieces of data are the same as those in thefollowing examples unless otherwise noted, and thus the repeateddescription thereof will be omitted below.

Next, an imaging optical system of Example 2 will be described. FIG. 2shows a cross-sectional view illustrating a configuration of the imagingoptical system of Example 2. In the imaging optical system of Example 2,the first optical system G1 is constituted by ten lenses of lenses L1 ato L1 j, and the second optical system G2 is constituted by nine lensesof lenses L2 a to L2 i. In addition, Table 4 shows lens data of theimaging optical system of Example 2, Table 5 shows data relating tospecifications, Table 6 shows data relating to aspherical coefficients,and FIG. 6 shows a diagram of aberrations.

TABLE 4 Example 2: Lens data (n and ν are based on the d line) SURFACERADIUS OF SURFACE NUMBER CURVATURE SPACING n ν *1 −28.4161 0.59141.58313 59.46 *2 3.1877 1.9307  3 9.5077 0.4223 1.80400 46.58  4 2.12151.4840  5 −3.1760 1.6897 1.60311 60.64  6 4.3955 0.0051  7 5.0478 0.55241.83481 42.72  8 44.6210 0.9073  9 −2.8724 1.2679 1.80000 29.84 10−3.5729 2.0894 11 9.8123 1.5594 1.59282 68.62 12 −3.1684 0.2067 1.7173629.52 13 −6.0100 0.9589 14 5.5703 1.6775 1.49700 81.61 15 −3.6845 0.19901.80518 25.46 16 8.6544 2.2997 *17  6.9267 1.1768 1.58313 59.46 *18 −5.2010 3.6773 19 4.4395 1.0397 1.84666 23.78 20 10.9265 2.3957 21−4.6100 1.0138 1.51742 52.43 22 6.4147 0.6609 23 −99.7684 0.8315 1.8000029.84 24 −6.1678 2.3912 25 5.6136 1.0559 1.59282 68.62 26 −17.12103.5400 27 ∞ 0.4475 (DIAPHRAGM) 28 2.6166 0.1477 1.51742 52.43 29 2.22660.8724 30 −2.1642 0.1433 1.84666 23.78 31 10.5923 0.7858 1.59282 68.6232 −3.4882 0.0049 1.59282 68.62 33 48.6216 0.8672 34 −3.7327 2.4441 3510.5646 0.9083 1.89286 20.36 36 −17.5673 3.0415 37 ∞ 4.2243 1.5163364.14 38 ∞ 0.0029

TABLE 5 Example 2: Specifications f′ −1.00 Bf′ 5.82 FNo. 2.06 2ω[°]126.2

TABLE 6 Example 2: Aspherical coefficients SURFACE NUMBER 1 2 KA−7.62985147E−06  −1.59640105E+00  A3 1.91408828E−02 3.78525744E−02 A47.79071137E−04 −2.63303267E−02  A5 −9.89629774E−04  3.31670557E−02 A61.08015681E−04 −2.57447646E−02  A7 1.63122617E−05 1.41563539E−02 A8−2.93147023E−06  −5.55663212E−03  A9 2.66031250E−08 1.56846843E−03 A103.80339069E−08 −3.25360687E−04  A11 −4.11032685E−09  4.96325958E−05 A12−3.02625387E−10  −5.34511402E−06  A13 1.33747722E−11 4.22571950E−07 A14−3.90030584E−12  −2.06020966E−08  A15 1.54060542E−12 2.09403135E−10 A164.04930765E−13 −4.16926444E−10  A17 0.00000000E+00 0.00000000E+00 A180.00000000E+00 0.00000000E+00 SURFACE NUMBER 17 18 KA 4.72767629E−01−1.34228925E+01 A3 −4.91751518E−03  −1.11356946E−02 A4 1.05764524E−02 1.61799985E−02 A5 −6.54558089E−03  −3.04716398E−03 A6 3.64498152E−03−2.31918247E−03 A7 −4.01192533E−03   1.26375715E−03 A8 2.62506077E−03−3.95728833E−04 A9 −8.30106731E−04   1.25063790E−04 A10 6.87459767E−05−2.49054453E−05 A11 1.77334354E−05  4.56941844E−07 A12 5.18467948E−06 6.99499362E−08 A13 −5.38536547E−06   2.54779603E−07 A14 1.25242824E−06−7.88546454E−08 A15 −1.10682377E−07   9.04308229E−09 A16 2.23983419E−09−6.33101039E−10

Next, an imaging optical system of Example 3 will be described. FIG. 3shows a cross-sectional view illustrating a configuration of the imagingoptical system of Example 3. The imaging optical system of Example 3 hasthe same lens number configuration as that in Example 2. In addition,Table 7 shows lens data of the imaging optical system of Example 3,Table 8 shows data relating to specifications, Table 9 shows datarelating to aspherical coefficients, and FIG. 7 shows a diagram ofaberrations.

TABLE 7 Example 3: Lens data (n and ν are based on the d line) SURFACERADIUS OF SURFACE NUMBER CURVATURE SPACING n ν *1 52.5341 0.5972 1.5831359.46 *2 2.8027 2.3214  3 11.3237 0.4264 1.80400 46.58  4 2.1599 1.6802 5 −2.7245 1.5025 1.60311 60.64  6 −3.5451 0.0051  7 5.3883 0.59661.83481 42.72  8 −793.2892 1.5071  9 −2.8089 1.3992 1.80000 29.84 10−3.6006 1.1288 11 10.4608 1.4124 1.59282 68.62 12 −3.1453 0.1936 1.7173629.52 13 −5.4261 0.7023 14 5.8797 1.5715 1.49700 81.61 15 −3.3228 0.19021.80518 25.46 16 7.8400 2.2877 *17  7.0627 1.2200 1.58313 59.46 *18 −5.6310 3.6208 19 4.8027 1.0728 1.84666 23.78 20 15.3423 2.1318 21−5.1283 0.9577 1.51742 52.43 22 6.6360 0.7944 23 −80.2773 0.8284 1.8000029.84 24 −6.5675 2.9250 25 6.6107 1.0225 1.59282 68.62 26 −14.30553.7544 27 ∞ 0.5019 (DIAPHRAGM) 28 2.8482 0.1521 1.51742 52.43 29 2.38260.8867 30 −2.2616 0.1453 1.84666 23.78 31 15.2410 0.7502 1.59282 68.6232 −3.4929 0.0049 33 84.7093 0.8300 1.59282 68.62 34 −3.7833 2.6338 3510.1154 0.8983 1.89286 20.36 36 −20.1689 3.0713 37 ∞ 4.2658 1.5163364.14 38 ∞ 0.0027

TABLE 8 Example 3: Specifications f′ −1.00 Bf′ 5.88 FNo. 2.12 2ω[°]126.6

TABLE 9 Example 3: Aspherical coefficients SURFACE NUMBER 1 2 KA−7.62987440E−06  −4.50211776E−01  A3 1.45528522E−02 3.31761059E−02 A47.71878026E−04 −2.54782717E−02  A5 −9.34295098E−04  3.18914598E−02 A61.03352289E−04 −2.45305383E−02  A7 1.54271141E−05 1.33484956E−02 A8−2.72924766E−06  −5.19201669E−03  A9 2.70844544E−08 1.45117474E−03 A103.52166938E−08 −2.97939276E−04  A11 −3.70029058E−09  4.50197003E−05 A12−2.74795466E−10  −4.80144694E−06  A13 1.37169643E−11 3.75865268E−07 A14−5.25704973E−12  −1.79165936E−08  A15 1.27601696E−12 1.82308650E−10 A163.55604225E−13 −3.60177701E−10  A17 0.00000000E+00 0.00000000E+00 A180.00000000E+00 0.00000000E+00 SURFACE NUMBER 17 18 KA 4.61874658E−01−1.35252030E+01 A3 −6.99253997E−03  −1.42198197E−02 A4 1.04169830E−02 1.59684585E−02 A5 −6.31224549E−03  −2.95889409E−03 A6 3.46931526E−03−2.21595129E−03 A7 −3.78428599E−03   1.18999835E−03 A8 2.45175777E−03−3.69946897E−04 A9 −7.67949673E−04   1.15769453E−04 A10 6.29630174E−05−2.27571703E−05 A11 1.60409670E−05  3.67481869E−07 A12 4.65681099E−06 5.89317440E−08 A13 −4.79058121E−06   2.26529118E−07 A14 1.10328635E−06−6.94965844E−08 A15 −9.64617926E−08   7.89814479E−09 A16 1.93108926E−09−5.73561631E−10

Next, an imaging optical system of Example 4 will be described. FIG. 4shows a cross-sectional view illustrating a configuration of the imagingoptical system of Example 4. In the imaging optical system of Example 4,the first optical system G1 is constituted by ten lenses of lenses L1 ato L1 j, and the second optical system G2 is also constituted by tenlenses of lenses L2 a to L2 j. In addition, Table 10 shows lens data ofthe imaging optical system of Example 4, Table 11 shows data relating tospecifications, Table 12 shows data relating to aspherical coefficients,and FIG. 8 shows a diagram of aberrations.

TABLE 10 Example 4: Lens data (n and ν are based on the d line) SURFACERADIUS OF SURFACE NUMBER CURVATURE SPACING n ν *1 198.7971 0.64511.58313 59.46 *2 3.1209 1.8593  3 10.5146 0.4608 1.80400 46.58  4 2.57572.1612  5 −2.9608 1.5682 1.60311 60.64  6 −3.5387 0.0055  7 6.20081.3089 1.83481 42.72  8 82.8756 0.8117  9 −3.0657 1.7106 1.80000 29.8410 −3.9061 1.1792 11 12.1231 1.8450 1.59282 68.62 12 −3.3382 1.84321.71736 29.52 13 −5.7610 0.4147 14 6.4969 1.8450 1.49700 81.61 15−3.6997 0.4489 1.80518 25.46 16 8.5451 2.3338 *17  8.6197 1.1889 1.5831359.46 *18  −5.7503 4.1673 19 6.1652 1.7301 1.84666 23.78 20 13.99771.6516 21 −6.3486 1.0462 1.51742 52.43 22 11.0818 0.9082 23 −38.61611.8434 1.80000 29.84 24 −7.4256 5.3454 25 9.0376 1.8432 1.59282 68.62 26665.2770 1.4221 27 −585.3151 1.8432 1.59282 68.62 28 −20.2843 5.1440 29∞ 0.2013 (DIAPHRAGM) 30 3.1704 0.2903 1.51742 52.43 31 2.6705 0.9468 32−2.6031 0.1549 1.84666 23.78 33 14.1022 0.7217 1.59282 68.62 34 −4.06850.0056 35 1211.7848 1.4617 1.59282 68.62 36 4.1344 3.0837 37 12.36831.8434 1.89286 20.36 38 −18.2321 3.3178 39 ∞ 4.6081 1.51633 64.14 40 ∞0.0026

TABLE 11 Example 4: Specifications f′ −1.00 Bf′ 6.35 FNo. 2.17 2ω[°]130.0

TABLE 12 Example 4: Aspherical coefficients SURFACE NUMBER 1 2 KA−7.77493017E−06  −5.23511927E−01  A3 1.32196373E−02 2.80785720E−02 A46.13630662E−04 −2.02040065E−02  A5 −6.87983406E−04  2.34216287E−02 A67.01982015E−05 −1.66758562E−02  A7 9.70393322E−06 8.39995040E−03 A8−1.59016534E−06  −3.02460050E−03  A9 1.44785309E−08 7.82593934E−04 A101.75375194E−08 −1.48736890E−04  A11 −1.71111872E−09  2.08051966E−05 A12−1.17316670E−10  −2.05399365E−06  A13 5.27972831E−12 1.48847046E−07 A14−1.82635827E−12  −6.56854664E−09  A15 4.32080585E−13 5.56961180E−11 A161.12386413E−13 −1.13146905E−10  A17 0.00000000E+00 0.00000000E+00 A180.00000000E+00 0.00000000E+00 SURFACE NUMBER 17 18 KA 4.09177993E−01−1.33610231E+01 A3 −5.67176323E−03  −1.17220410E−02 A4 8.08616925E−03 1.28762295E−02 A5 −4.65084992E−03  −2.16166099E−03 A6 2.35698666E−03−1.50656379E−03 A7 −2.38156340E−03   7.48518482E−04 A8 1.42823954E−03−2.15480139E−04 A9 −4.14113147E−04   6.24176095E−05 A10 3.14291163E−05−1.13583105E−05 A11 7.41161846E−06  1.72108112E−07 A12 1.99157681E−06 2.43105207E−08 A13 −1.89706362E−06   8.97111371E−08 A14 4.04449444E−07−2.54737911E−08 A15 −3.27328612E−08   2.67893276E−09 A16 6.06547139E−10−1.80665828E−10

Table 13 shows values corresponding to Conditional Expressions (1) to(7) of the imaging optical systems of Examples 1 to 4. Meanwhile, the dline is used as a reference wavelength in all the examples, and valuesshown in the following Table 13 are equivalent to those at thisreference wavelength.

TABLE 13 EXPRESSION CONDITIONAL NUMBER EXPRESSION EXAMPLE 1 EXAMPLE 2EXAMPLE 3 EXAMPLE 4 (1) H*|f|/(L*I) 0.065 0.065 0.075 0.052 (2) I/dl0.456 0.494 0.467 0.402 (3) b/a 5.61 5.62 5.72 6.01 (4) H*f²/(fo*I²)1.090 0.998 1.144 0.851 (5) fo/|f| 1.29 1.41 1.41 1.62 (6) enp/I 1.391.40 1.61 1.38 (7) (Rpr + Rmf)/ 0.33 0.41 0.50 0.38 (Rpr − Rmf)

From the above-mentioned data, it can be understood that the imagingoptical systems of Examples 1 to 4 all satisfy Conditional Expressions(1) to (7), and are imaging optical systems which are configured suchthat the total angle of view is equal to or greater than 100° to have awide angle of view, while various aberrations are appropriatelycorrected and a lens diameter is kept small.

Next, a projection-type display apparatus according to an embodiment ofthe present invention will be described. FIG. 9 is a schematicconfiguration diagram of a projection-type display apparatus accordingto the embodiment of the present invention. A projection-type displayapparatus 100 shown in FIG. 9 includes an imaging optical system 10according to an embodiment of the present invention, a light source 15,transmission-type display devices 11 a to 11 c as light valvescorresponding to respective beams of colored light, dichroic mirrors 12and 13 for color decomposition, a cross dichroic prism 14 for colorsynthesis, capacitor lenses 16 a to 16 c, and total reflection mirrors18 a to 18 c for deflecting an optical path. Meanwhile, in FIG. 9 , theimaging optical system 10 is schematically shown. In addition, anintegrator is disposed between the light source 15 and the dichroicmirror 12, but is not shown in FIG. 9 .

White light from the light source 15 is decomposed into three coloredlight fluxes (G light, B light, and R light) by the dichroic mirrors 12and 13. The decomposed light fluxes are then incident on thetransmission-type display devices 11 a to 11 c corresponding to therespective colored light fluxes through the capacitor lenses 16 a to 16c, respectively, and are optically modulated. The modulated light fluxesare color-synthesized by the cross dichroic prism 14, and then areincident on the imaging optical system 10. The imaging optical system 10projects an optical image of light optically modulated by thetransmission-type display devices 11 a to 11 c onto a screen 105.

FIG. 10 is a schematic configuration diagram of a projection-typedisplay apparatus according to another embodiment of the presentinvention. A projection-type display apparatus 200 shown in FIG. 10includes an imaging optical system 210 according to the embodiment ofthe present invention, a light source 215, DMDs 21 a to 21 c as lightvalves corresponding to respective beams of colored light, totalinternal reflection (TIR) prisms 24 a to 24 c for color decompositionand color synthesis, and a polarization separation prism 25 thatseparates illumination light and projected light. Meanwhile, in FIG. 10, the imaging optical system 210 is schematically shown. In addition, anintegrator is disposed between the light source 215 and the polarizationseparation prism 25, but is not shown in FIG. 10 .

White light from the light source 215 is reflected from a reflectingsurface inside the polarization separation prism 25, and then isdecomposed into three colored light fluxes (G light, B light, and Rlight) by the TIR prisms 24 a to 24 c. The respective colored lightfluxes after the decomposition are incident on the DMDs 21 a to 21 ccorresponding thereto and are optically modulated. The modulated lightfluxes travel through the TIR prisms 24 a to 24 c again in an oppositedirection and are color-synthesized. The synthesized light passesthrough the polarization separation prism 25 and is incident on theimaging optical system 210. The imaging optical system 210 projects anoptical image of light optically modulated by the DMDs 21 a to 21 c ontoa screen 205.

FIG. 11 is a schematic configuration diagram of a projection-typedisplay apparatus according to still another embodiment of the presentinvention. A projection-type display apparatus 300 shown in FIG. 11includes an imaging optical system 310 according to the embodiment ofthe present invention, a light source 315, reflection-type displaydevices 31 a to 31 c as light valves corresponding to respective beamsof colored light, dichroic mirrors 32 and 33 for color separation, across dichroic prism 34 for color synthesis, a total reflection mirror38 for optical path deflection, and polarization separation prisms 35 ato 35 c. Meanwhile, in FIG. 11 , the imaging optical system 310 isschematically shown. In addition, an integrator is disposed between thelight source 315 and the dichroic mirror 32, but is not shown in FIG. 11.

White light from light source 315 is decomposed into three colored lightfluxes (G light, B light, and R light) by the dichroic mirrors 32 and33. The respective colored light fluxes after the decomposition areincident on the reflection-type display devices 31 a to 31 ccorresponding to the respective colored light fluxes through thepolarization separation prisms 35 a to 35 c, respectively, and areoptically modulated. The modulated light fluxes are color-synthesized bythe cross dichroic prism 34, and then are incident on the imagingoptical system 310. The imaging optical system 310 projects an opticalimage of light optically modulated by the reflection-type displaydevices 31 a to 31 c onto a screen 305.

FIGS. 12 and 13 are appearance diagrams of a camera 400 which is animaging apparatus of an embodiment of the present invention. FIG. 12shows a perspective view when the camera 400 is seen from the frontside, and FIG. 13 is a perspective view when the camera 400 seen fromthe rear surface side. The camera 400 is a single-lens digital camera,having no reflex finder, which has an interchangeable lens 48 detachablymounted therein. The interchangeable lens 48 has an imaging opticalsystem 49 which is an optical system according to the embodiment of thepresent invention housed within a lens barrel.

This camera 400 includes a camera body 41, and is provided with ashutter button 42 and a power button 43 on the upper surface of thecamera body 41. In addition, operating portions 44 and 45 and a displayportion 46 are provided on the rear surface of the camera body 41. Thedisplay portion 46 is used for displaying a captured image or an imagewithin an angle of view before image capture.

An imaging aperture on which light from an imaging target is incident isprovided on the front central portion of the camera body 41, a mount 47is provided at a position corresponding to the imaging aperture, and theinterchangeable lens 48 is mounted onto the camera body 41 through themount 47.

The camera body 41 is provided therein with an imaging device (notshown) such as a charge coupled device (CCD) that outputs an imagingsignal according to a subject image formed by the interchangeable lens48, a signal processing circuit that processes the imaging signal whichis output from the imaging device to generate an image, a recordingmedium for recording the generated image, and the like. In this camera400, a still image or a moving image can be captured by pressing theshutter button 42, and image data obtained by this image capture isrecorded in the recording medium.

Hereinbefore, the present invention has been described throughembodiments and examples, but the imaging optical systems of the presentinvention are not limited to those of the above examples, and can bevariously modified. For example, it is possible to appropriately changethe radius of curvature, the surface spacing, the refractive index, andthe Abbe number of each lens.

In addition, the projection-type display apparatuses of the presentinvention are also not limited to the above configurations. For example,the light valves which are used and the optical members which are usedfor light flux separation or light flux synthesis are not limited to theabove configurations, and can be modified in various forms.

In addition, the imaging apparatus of the present invention is also notlimited to the above configuration, and can also be applied to, forexample, a single-lens reflex camera, a film camera, a video camera, andthe like.

EXPLANATION OF REFERENCES

-   -   10, 210, 310: imaging optical system    -   11 a to 11 c: transmission-type display device    -   12, 13, 32, 33: dichroic mirror    -   14, 34: cross dichroic prism    -   15, 215, 315: light source    -   16 a to 16 c: capacitor lens    -   18 a to 18 c, 38: total reflection mirror    -   21 a to 21 c: DMD    -   24 a to 24 c: TIR prism    -   25, 35 a to 35 c: polarization separation prism    -   31 a to 31 c: reflection-type display device    -   41: camera body    -   42: shutter button    -   43: power button    -   44, 45: operating portion    -   46: display portion    -   47: mount    -   48: interchangeable lens    -   49: imaging optical system    -   100, 200, 300: projection-type display apparatus    -   105, 205, 305: screen    -   400: camera    -   G1: first optical system    -   G2: second optical system    -   L1 a to L2 j: lens    -   PP: optical member    -   Sim: image display surface    -   St: aperture diaphragm    -   wa: on-axis light flux    -   wb: light flux of maximum angle of view    -   Z: optical axis

What is claimed is:
 1. An imaging optical system capable of projectingan image, displayed on an image display device disposed on areduced-side conjugate plane, as a magnified image on a magnified-sideconjugate plane, the system comprising, in order from a magnified side:a first optical system which is constituted by a plurality of lenses;and a second optical system which is constituted by a plurality oflenses, wherein the second optical system forms the image displayed onthe image display device as an intermediate image, the first opticalsystem forms the intermediate image on the magnified-side conjugateplane, a height of a principal ray of light having a maximum angle ofview becomes maximum on a lens surface of the imaging optical system ona most magnified side, among heights of principal rays of light having amaximum angle of view on respective lens surfaces, a total angle of viewis equal to or greater than 100°, and the following ConditionalExpression (1) is satisfied,0.03<H×|f|/(L×I)<0.09  (1) where H is a height of the principal ray oflight having a maximum angle of view on a plane orthogonal to an opticalaxis through a point of intersection between the lens surface on themost magnified side and the optical axis, f is a focal length of theimaging optical system, L is a distance on the optical axis between thelens surface on the most magnified side and a lens surface on a mostreduced side, and I is a maximum image height on a reduced side.
 2. Theimaging optical system according to claim 1, wherein the followingConditional Expression (1-1) is satisfied,0.04<H×|f|/(L×I)<0.08  (1-1)
 3. The imaging optical system according toclaim 1, wherein the following Conditional Expression (6) is satisfied,1<enp/I<2  (6) where enp is a distance on the optical axis from the lenssurface on the most magnified side to a pupil position on the magnifiedside.
 4. The imaging optical system according to claim 3, wherein thefollowing Conditional Expression (6-1) is satisfied,1.38≤enp/I<2  (6-1).
 5. The imaging optical system according to claim 1,wherein an optical element on the most magnified side of the firstoptical system is a lens.
 6. The imaging optical system according toclaim 3, wherein an optical element on the most magnified side of thefirst optical system is a lens.
 7. The imaging optical system accordingto claim 1, wherein the first optical system includes at least twomeniscus lenses having a surface convex toward the magnified side. 8.The imaging optical system according to claim 3, wherein the firstoptical system includes at least two meniscus lenses having a surfaceconvex toward the magnified side.
 9. The imaging optical systemaccording to claim 5, wherein the first optical system includes at leasttwo meniscus lenses having a surface convex toward the magnified side.10. The imaging optical system according to claim 1, wherein the firstoptical system includes at least three biconvex lenses.
 11. The imagingoptical system according to claim 3, wherein the first optical systemincludes at least three biconvex lenses.
 12. The imaging optical systemaccording to claim 5, wherein the first optical system includes at leastthree biconvex lenses.
 13. The imaging optical system according to claim7, wherein the first optical system includes at least three biconvexlenses.
 14. The imaging optical system according to claim 1, wherein thesecond optical system includes a biconcave lens and two biconvex lenseslocated adjacent to a reduced side of the biconcave lens.
 15. Theimaging optical system according to claim 3, wherein the second opticalsystem includes a biconcave lens and two biconvex lenses locatedadjacent to a reduced side of the biconcave lens.
 16. The imagingoptical system according to claim 5, wherein the second optical systemincludes a biconcave lens and two biconvex lenses located adjacent to areduced side of the biconcave lens.
 17. The imaging optical systemaccording to claim 1, wherein a lens on the most reduced side of thesecond optical system is biconvex.
 18. The imaging optical systemaccording to claim 3, wherein a lens on the most reduced side of thesecond optical system is biconvex.
 19. A projection-type displayapparatus comprising: a light source; a light valve on which light fromthe light source is incident; and the imaging optical system accordingto claim 1 as an imaging optical system that projects an optical imageof light optically modulated by the light valve onto a screen.
 20. Animaging apparatus comprising the imaging optical system according toclaim 1.